>The individual republics organized multi-party elections in 1990, and the former communists mostly failed to win re-election, while most of the elected governments took on nationalist platforms, promising to protect their separate nationalist interests. In multi-party parliamentary elections nationalists defeated re-branded former Communist parties in Slovenia on 8 April 1990, in Croatia on 22 April and 2 May 1990, in Macedonia 11 and 25 November and 9 December 1990, and in Bosnia and Herzegovina on 18 and 25 November 1990.
what happened is communism as a political formula no longer worked, and the strongest constituent element in Yugoslavia, Serbia, decided to pivot towards a new political formula which was stable for them, which was Serbian nationalism. and this created a new stable point that caused the remaining three republics to break away.